Roller grin ding-mill



2 Sheets-Sheet 1. J. mwvsolv.

ROLLER GRINDING MILL.

N0.260,669. Patented July 4,1882;

' 2 Sheets-Sheet J. DAWSON. ROLLER GRINDING MILL. y

ma July 4, 188.2.

i 7 f 7 f..

UNITED STATES PATENT OFFICE.

JAMES RAWSON', orl CLEAR GRIT, MINNESOTA, ASsIcNOR OF ONEHA LF To ROBERT L. DOWNTON, on ST. LOUIS, MISSOURI.

ROLLER GR|ND|NGMILL.

SPECIFICATION forming part of Lettersvlatent 1\To.` 260,669, dated July 4, 1882.

Application filed June 30, 1879.

referencev being made to the accompanying and in which- Figure 1 represents an elevation of the gearing side of the machine embodying my invention, showing in plain and dotted nlines the mechanism by which the several pairs of rolls are operated. Fig. 2 represents a partial end elevation of the grooved rolls. Fig. 3 representS a vertical central longitudinal section of the machine, Fig. 4, a partial plan View of the grooved rolls and the operating mechanism.

My invention relates to certain new and useful improvements in the class of grindingmills known as roller-mills, and it consists essentially in a novel` dress applied to the rolls 5 drawings, forming a part of this specitication,

. and, further, in novel combination and arrangement of parts, all as will be hereinafter fully described, and specically pointed out in the claims.

Similar letters of reference cur indicate like parts.

A A represent the standards, secured together by the crossties ct, that constitute the frame which supports the-adjustable and fixed bearing-boxes for the journals ot' the pairs of smooth and grooved facedrolls B B' and D D. The pairs ot' smooth-facedv rolls B B are operated through the medium ot' gear-wheels E E' of like diameter, for producing a uniform rate ot' speed, While the grooved rolls D D areoperated by gear-wheels F F of different diameter, to revolve at dierent peripheral speeds. These Several pairsl of rolls are driven by means of pulleys M, keyed to the axles of one roll of each pair, and which are of graduated size, the upper one being the largest, said pulleys receiving motion from a single belt, m, which moves in the direction indicated by the arrows from a suitable driving-wheel around the pulleys, as shown in Fig. 1, therebygreatly utilizing the power required for operating the several pairs of. rolls.

H represents the supply or feed hopper arwheretliey ocranged on top of the machine, and provided with the usual feed-roll, G, in the bottom thereof, and adjustable side for regulating theliow ot' the material to the rst or upper pair of rolls; and L, the open-bottomed troughs, composed of the inclined gatheiboards n, arranged between the pairs of rolls for receiving and delivering the material passing between each pair of rolls to the next succeed- Y ingpair ot' rolls; and L', the receiving box or hopper arranged below thelastpair or groovedfaced rolls.

I represents the usual adjustingscrews for regulating the distance between the rolls.

To the rolls D D', I applya dress composed of grooves cut or otherwise formed on their peripheries like the teeth of single-cut files, and take in one roll a spiral direction to the left and in the other a spiral direction to theright, or reversely to each other, and the angle at which the grooves are twisted or run may l materially vary in different pairs of rolls, or in one roll it maybe greater than in the other; but `I prefer to have them arranged at an angle of about thirty-five degrees to the axis ot' each roll.

It will be observed that the teeth or ribs formed by the grooves (taking the rolls D for an illustration) upon the advancing Side d are of easy bevel, but on the other side fall away rapidly, the longer sides d of the teeth or ribs constituting the active or grinding surface ot' the rolls, and facing each other as the rolls revolve. These grooved rolls D D', having the dress constructed as above described, operate in a manner essentially differentfrom the sharpribbed rolls heretofore used in this vclass ot' mills, the grain being operated upon in such manner that the starchy and glut-inous portions are merely pulverized, while the bran and germ are bruised and rubbed, and at the same time, by the spiral direction the grooves take on the periphery of the rolls, the material is carried a short distance lengthwise of the rolls before passing between the ribs, thus producing a rolling or twisting action on the bran and germ, and thereby it is left in such condition as to be easily and readily removed from the middlings and our by the ordinary bolting process, while with the Sharp-ribbed rolls heretofore used the bran and germ are cut into ICO such fine particles that a large proportion will pass through the bolting-cloth with the middlings and flour during the bolting process, and thus require various subsequent manipulations to remove them.

The number of grooves in the rolls may vary for different degrees of iineness or different grades of work, or according to the substance to be reduced.

The operation ot' my improved machine is as follows: The grain'from the hopper passes between the first or upper pair of smooth-faced rolls, having comparatively slow rate of speed, which crack or break it into large granular particles, which then pass between the next pair ot' smooth-faced rolls, which are regulated to reduce it to a still finer condition, rendering the granular particles more susceptible to the groovefaced rolls between which they subseqnently pass, thereby cansin g a speedy reduction of the granular particles to the desired condition, readily separating the germ and bran therefrom, and leaving it in the condition before described, so as to be easily and readily removed from the middlings and flour by the ordinary bolting process.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a roller grinding-mill, thecm'hbination of the rolls D D', having a dress composed ot ribs or teeth running in a spiral direction, the

ribs or teeth of one roll running reversely toperipheral rates of speed, the roll D' krunning faster than roll D, and having a dress composed of ribs or teeth running in a spiral direction, the ribs or teeth of one roll running reversely to the ribs or teeth of the other roll, with the sides d of said ribs or teeth ot' easy bevel and their opposite sides of sharper bevel, whereby the corresponding sides d of the ribs or teeth ofthe rolls constitute the active grinding-surfaces, substantially as specified.

In testimony that I claim the foregoing as my own I have affixed my signature in presence ot' two witnesses.

JAMES DAIVSON.

Witnesses:

S. S. DEMAREY, BARNABAs DAWSON.

r4o of-the rolls D D', geared to revolve at different 

